Primordial blackholes [1]}, [2]} are a viable candidate for dark matter [3]}, [4]} and may constitute all or a part of the dark matter relic density today.
Recent studies of primordial blackholes as a dark matter candidate include Refs. [5]}, [6]}, [7]}, [8]}, [9]}, [10]}.
Unlike astrophysical blackholes, primordial blackholes may form in the early Universe through the gravitational collapse of large over-density regions. See e.g. Refs. [11]}, [10]}, [13]}, [14]} for reviews.
